Up to now, various imaging apparatuses which are equipped with a solid-state imaging device having pairs of two photoelectric conversion elements have been suggested, where the two photoelectric conversion elements obtain signals with different sensitivities to expand a dynamic range (a D range) (e.g., see Patent Documents 1 to 3).
An imaging apparatus disclosed in Patent Document 1 has a solid-state imaging device that includes pairs of pixel sections, each pair having two photoelectric conversion elements, which have red color filters different in wavelength selectivity provided thereabove, respectively, pairs of pixel sections, each pair having two photoelectric conversion elements, which have green color filters different in wavelength selectivity, respectively provided thereabove, and pairs of pixel sections, each pair having two photoelectric conversion elements, which have blue color filters different in wavelength selectivity provided thereabove, respectively. Thus, an improvement in color reproducibility is realized by combining signals obtained from the two photoelectric conversion elements of each pair of pixel sections are combined. Furthermore, the dynamic range can also be expanded by providing a sensitivity difference between the two photoelectric conversion elements of each pair of pixel sections (by changing a structure or an exposure time in the two photoelectric conversion elements).
In the solid-state imaging device having the configuration disclosed in Patent Document 1, when the quality of image is taken into consideration, it would be necessary to review which one of the two photoelectric conversion elements should be made to have a higher sensitivity in each pair of pixel sections. However, Patent Document 1 does not describe a specific example for the case in which the sensitivity difference is provided between the two photoelectric conversion elements of each pair of pixel sections.
In Patent Document 2, a solid-state imaging device that holds color filters having different spectral characteristics on an upper side thereof and includes primary and secondary photosensitive sections whose light-receiving areas are different from each other is disclosed. With this solid-state imaging device, it is also possible to expand a dynamic range.
However, Patent Document 2 is mainly directed to an improvement in discrimination precision of an illuminating light source, and does not describe color reproducibility.
In Patent Document 3, a solid-state imaging device that have a plurality of pairs of two photoelectric conversion elements, which are equal to or different from each other in photoelectric conversion sensitivity is disclosed. However, only the expansion of a dynamic range is mentioned, but the improvement of color reproducibility is not described.